One of the most common extinguishing agents for automatic fire suppression are gas systems, especially HFCs, inert gases and CO2.
The growing concern for the environment and the need to reduce gases with high global warming effect (GWP) are leading consumers to opt for organic gases and regulating bodies to limit or prohibit the use of HFC. This new regulatory framework has an important effect on the choice of the extinguishing agent used in fire extinguishing systems. Limiting the use of HFCs and changing consumer preferences toward gases less harmful to the environment has led to a growth in consumption of inert gases, which are 100% organic.
Inert gases used in fire extinguishing are nitrogen, argon and combinations thereof, alone or with other gases. Due to their nature, inert gases are stored in gaseous state rather than in fluid state requiring storage pressures higher than HFC. Currently the most common are 150 bars, 200 bars and 300 bars, but other pressures can be operated. This requires that all elements of the installation must be designed and manufactured to withstand a pressure higher than the working or storage pressure, which according to regulations must be one and half times the working or storage pressure. Obviously, the higher the pressure that an element must resist, greater is the cost of manufacture, and therefore it is less competitive.
On the other hand, the higher the pressure of the gas, greater will be the distance covered and less the time of discharge. However, high discharge pressures generate overpressure in the space to be protected, which can damage the contents of the room; therefore, it is necessary to provide anti-overpressure measures that make installations more burdensome.
In firefighting installations using inert gas, the gas is stored in a cylinder in which a valve is assembled that controls the discharge of said gas. In standard installations the valve does not regulate the gas outlet, whereby the outlet pressure of the valve is the same as the pressure in which the gas is stored in the cylinder, that is, if the gas pressure in the container is 300 bars, the initial outlet pressure will also be 300 bars. The pressure is maintained at 300 bars on all the components until reaching the collector connection with the pipe where a restrictor with a disc with an opening is placed reducing the pressure to 60 bars. These installations are also called opening installations.
There are also the so-called constant flow installations, in which the valve regulates the outlet pressure of the gas, so that different pressures to those of the stored gas are achieved. This enables using lower pressure components and, therefore, they are cheaper.
It is also important to note that the amount of gas required for a proper extinction, within the parameters defined by regulations, is defined by the hydraulic calculation. A hydraulic calculation that is made correctly should take into account the highest peak of pressure, even if it is only for milliseconds. The hydraulic calculation takes into account the behaviour of the pressure and gas flow from the discharge port of the valve, thus a regulated but constant discharge will be easier to reproduce in the hydraulic calculation algorithm than an inconstant discharge, with pressure peaks or with pulsating pressures.
Another important factor for calculating the amount of gas is the outlet flow rate of the valve; therefore, it is critical in the design of the valve that the regulation is made with minimum load loss and with the maximum free flow section possible. A constant and consistent discharge helps the hydraulic calculation to be more efficient and permits the reduction of the diameter of the discharge pipe, making the installation more economic.
An installation of automatic extinguishing through gas essentially comprises the following:                a gas containment vessel, usually called cylinder or tank        a discharge valve        release installations        pressure control installations (pressure gauges, pressure switches . . . )        a gas        connecting tubes        non-return valves        pipes and collectors to channel the gas        directional valves        other non-relevant elements such as hardware        a hydraulic calculation to ensure that the installations discharge under certain regulatory conditions. This means that it discharges a certain amount of gas in a limited time. Among other parameters, this is determined by the discharge pressure of the gas and the outlet flow rate of this gas.        
The gas discharge valve has several main functions: retaining the gas in the cylinder when it is at rest; discharging the gas as needed; and, in the case of regulated valves, reducing the outlet pressure.
Each gas valve comprises a body, chambers and internal passages for gas to flow through and a means of releasing or opening. In addition, most current valves also incorporate a main shaft which shuts off the outlet of gas, and a spring that helps its operation.
As the closest documents of the state of the art to the object of the present invention, should be mentioned the following: WO2006/108931/EP1869534B1/U.S. Pat. No. 8,079,567B2 (Siemens); WO2004/079678 (Fike Corp.); WO2007/073390 (Chubb LTD); EP2241794A1 (LPG Técnicas en Extinción de Incendios SL).
The patent WO2004079678 (Fike) describes a system with a regulated discharge valve. This valve regulates the outlet pressure of the gas balancing the pressure between the different effective surfaces of several chambers, the opening and closing effect of a moveable shutter and the scaling of a spring that biases the shutter. The main element that regulates the gas is the filling and emptying of a chamber and the force of a spring which means that the regulation is pulsating, whereby a consistent regulation is not achieved. In addition, the correct functioning of this system depends on the balance with the spring pressure, rather, with its scaling, and due to the size of those springs achieving uniformity is productively very expensive, so it is likely that there be a variation between the different units, therefore the discharge pressure varies. If in the scaling of the spring a significant variation is allowed, this causes the regulation of one valve to another to vary quite a lot and affects the accuracy of the hydraulic calculation. In fact, the valve has a manual adjustment screw.
On the other hand, this type of regulation has the drawback that the dynamic balance achieved during the discharge is different from the static balance, which means that there is a pressure peak at the initial time of discharge. This valve has a very important problem, which consists in its not achieving the pressure balance if, for any reason, the duct outlet or installation does not allow discharge. That is, if the duct outlet is blocked, for example due to a malfunction of a directional valve, the discharge pressure could increase up to 300 bars, which is a risk if the adequate overpressure measures were not taken, but it also entails that, for the hydraulic calculation, the outlet pressure of 300 bars must be taken into consideration. Another reason for an improper balance of pressures is that the spring loses tension over time, resulting in an uncertainty in not knowing exactly at what pressure it will regulate. In addition, the spring can be compressed as a block into its opening, which prevents it from regulating the valve.
Patent EP2241794A1 (LPG) also describes a regulated discharge valve. As the previously described valve from the Fike Corporation, regulation is achieved between different effective surfaces and a mobile element, a shutter, which moves by opening and closing the outlet passageway. In this case, the balance is achieved using a coil spring, with the same scaling problems already mentioned above, since for the scaling of the spring to be exact it must be regulated one by one manually. Unlike the Fike valve, this valve needs pressure to push down a piston which allows the outlet of gas and, therefore, the operation of flows and balances is different.
However it presents exactly the same problem of dynamic balance other than static balance. In this case, the chamber design prevents that the pressure reaches 300 and it is regulated at about 100 bars, but this pressure entails the use of components and pipes of greater pressure, and therefore of higher manufacturing cost. At the same time, if the gas outlet is blocked in a haphazard way, the pressure of the gas will increase one and a half times above the discharge pressure desired, since to achieve the balance of pressures, it needs the outlet port to be open. If this is closed, the balance is achieved at a pressure greater than that desired.
Patent WO 2006/108931 (Siemens) also describes a regulated discharge valve of similar operation to that from LPG, and thus, with the same problems. Additionally, in this case, the designs of the chambers and passage ways are very small; hence the outlet flow rate is very low, which makes it a fairly inefficient valve for discharge. The lower the flow rate, the more time it takes to discharge.
The three valves briefly described have approximate outlet pressures and important variations from one valve to another.
The objective of the present invention is, therefore, the development of a new valve of the type mentioned that solves the indicated disadvantages which the hitherto known valves have, and which are summarised, basically, in:                that the regulation of the outlet pressure is performed based on the geometry of the valve for its reduction with respect to the pressure stored;        that the gradual loss of pressure of the gas contained in the cylinder, upon opening the valve, affects the outlet pressure;        that the peak of pressure that occurs at the time of opening of the valve must be withstood by said valve and by the other elements of the installation;        that the spring is always manufactured with exact precision and scaled to not vary in its work of retention or affect the outcome of the outlet pressure obtained;        that the valve must be designed, in each case, depending on the pressure under which the gas is stored in the cylinder;        that the outlet flow is perpendicular to the inlet flow, and therefore to the axis of the mouth of the cylinder, limiting the design of the arrangements of the installation;        that allows a greater pipe route;        that has a greater discharge flow;        that must be suppressed by the scaling springs that limit the discharge flow; and        that the valve can be regulated at various discharge pressures.        
Finally, it should be noted that a valve regulated under pressures below 60 bars brings significant advantages to the installation. The more load pressure of the gas, the greater the volume that can be placed in a cylinder and therefore less cost per Kg/m3 of gas. The other components of a system and their cost are determined largely by the pressure to which they will be subjected in a discharge. The lower the discharge pressure the lower the cost of the components. Therefore the cost of installation is determined by a balance between the pressure under which the gas is stored in the cylinder and the pressure at the time of discharge. A lower discharge pressure also entails less excess pressure in the protected room and, therefore, lower costs of installation. Significant savings are generated below 60 bars.